30 dwell with only the techt sounds a bit too ambitious. I think 35 is as far as it will go maybe one to 2 clicks lower after break in.
Since it's chronoing at 290 at 40 dwell, That would mean you turned the reg down already from stock.

Keep the dwell at 40 if it's shooting fine there. The idea for the techt bolt was to lower internal pressure. Not to lower dwell.